Wireless communication systems, such as cellular voice and data networks, typically include multiple wireless access nodes spread over a geographic area through which wireless communication devices can register and receive wireless access to communication services. In many examples, the wireless communication devices are mobile, and can move between wireless coverage areas, such as sectors, of the wireless access nodes.
The Long Term Evolution (LTE) protocol (also known as Evolved Universal Terrestrial Radio Access Network, or E-UTRAN) is a wireless communication protocol developed from GSM and 3GPP cellular communication standards. LTE is the first GSM/3GPP standard that is fully IP and packet-based. LTE can be fully integrated into 2G and 3G cellular infrastructure.
LTE was developed to provide improved performance and better spectral efficiency to cellular networks. LTE supports high data rates for services such as voice over IP (VOIP), streaming multimedia, videoconference, and high-speed cellular modem services. LTE supports flexible carrier bandwidths, as well as Time Division Duplex (TDD) and Frequency Division Duplex (FDD) communication modes. LTE was designed with a scalable carrier bandwidth from 1.4 MHz to up to 20 MHz. The bandwidth that is used depends of the frequency band and the amount of spectrum available to a network operator.
LTE uses the concept of a resource block, which is a block of 12 subcarriers in one slot. A transport block is a group of resource blocks with a common modulation/decoding. The physical interface is a transport block, which corresponds to the data carried in an allocated period of time for a particular wireless device in communication with a wireless communication network. Each radio subframe is one millisecond long. Allocations may be valid for one or more Transmission Time Intervals (TTIs), where each TTI is one subframe (i.e., one millisecond).
The MAC layer adds a header and performs padding to fit the MAC SDU into the TTI. The MAC layer submits the MAC PDU to the physical layer for transmitting the MAC PDU onto a physical channel. The physical channel transmits the data into slots of the sub frame.
Overview
Systems, methods, and software for dynamic modulation change while generating a MAC PDU in a LTE wireless network are provided herein. In one example, a method for dynamic modulation change while generating a Media Access Control (MAC) Protocol Data Unit (PDU) in a Long Term Evolution (LTE) protocol wireless network includes receiving in an evolved Node-B (eNB) a packet and a Channel Quality Indicator (CQI) from a User Equipment (UE), determining whether padding is needed in the MAC PDU, and if padding is needed, the eNB selecting a slower modulation scheme and coding rate than is specified by the CQI, wherein the selected slower modulation scheme and coding rate are selected so as to substantially eliminate padding in the MAC PDU, and transmitting the MAC PDU using the selected slower modulation scheme and coding rate.
In another example of a method for dynamic modulation change while generating a MAC PDU in a LTE protocol wireless network includes receiving a packet and a Channel Quality Indicator (CQI) in an evolved Node-B (eNB) from a User Equipment (UE), generating a padded MAC1 comprising the MAC plus padding and a MAC2 comprising the MAC, calculating a MAC1 modulation scheme and coding rate and a MAC2 modulation scheme and coding rate, if the number of MAC1 Resource Blocks (MAC1 RBs) are not equal to the number of MAC2 RBs, then transmitting the MAC PDU using the CQI, and if the number of MAC1 RBs are equal to the number of MAC2 RBs, then: setting the CQI to a next slower CQI, recalculating the MAC2 modulation scheme and coding rate according to the next slower CQI, if the number of MAC1 RBs are equal to the number of MAC2 RBs, then branching back to select a new next slower CQI, and if the number of MAC1 RBs are not equal to the number of MAC2 RBs, then selecting a slower modulation scheme and coding rate as specified by the next slower CQI and transmitting the MAC PDU using the next slower CQI, wherein the selected slower modulation scheme and coding rate are selected so as to substantially eliminate padding in the MAC PDU.
In another example, a LTE protocol evolved Node-B (eNB) for dynamic modulation change while generating a MAC PDU in a LTE wireless network is presented. The eNB includes a transceiver system configured to receive a packet and a Channel Quality Indicator (CQI) from a User Equipment (UE) and a processing system coupled to the transceiver system and configured to determine whether padding is needed in the MAC PDU, if padding is needed, select a slower modulation scheme and coding rate than is specified by the CQI, wherein the selected slower modulation scheme and coding rate are selected so as to substantially eliminate padding in the MAC PDU, and transmit the MAC PDU using the selected slower modulation scheme and coding rate.